Studies of Binocular Vision have proceeded along two parallel tracks: psychophysics and neuroanatomy. The psychophysical work emphasizes the use of stereoblindness as a technique for dissecting the normal stereoscopic mechanism. The principal psychophysical finding obtained during the past year is a demonstration of a strong correlation between fixation disparity and stereoblindness. Additional psychophysical findings bear upon the details of the stereoscopic mechanism, and in particular with an examination of the equidistance tendency and its relation to disparity processing. Neuroanatomical studies have been concerned both with the development and structure of the visual pathway. A study of myelin formation in the postnatal optic tract continues, as well as a closer look at the myelination process itself. However, our most exciting advance is the beginnings of some insight into the abnormalities associated with crosseyedness in ordinary, wild-type cats. Our data are suggesting that asymmetric cortical development together with defective midbrain (pretectal) structures are key factors underlying squint in cats. BIBLIOGRAPHIC REFERENCES: Stereopsis with large disparities: Discrimination and depth magnitude. J. Foley, W. Richards, and T.H. Applebaum. Vision Res., 15: 417-421 (1975). Broad band spatial filters in the human visual system. R. Spitzberg and W. Richards. Vision Res., 15: 837-841 (1975).